Networks can be found in many environments, including computer equipment rooms, telephone provider central offices and/or switching centers, and/or manufacturing plant instrumentation centers and/or control rooms. Frequently, networks include at least one circuit board assembly that powers, conditions, modifies, and/or processes a signal, noise, interference, etc. traveling on a circuit of the network.
Each circuit board assembly can be mounted in a rack or other multi-card mounting structure containing a multitude of other circuit board assemblies, all of which can be contained in an electrical device enclosure. Because during operation each such circuit board assembly can generate a substantial amount of heat, there can be a need to exhaust the heat from the enclosure. Yet conventional approaches to exhausting the heat can result in a system that creates too much acoustic noise external to the enclosure, fails to adequately prevent and/or contain flames generated from a fire within the enclosure, and/or fails to prevent unsafe access to the contents of the enclosure.
U.S. Pat. No. 6,198,627, issued to Roehling et al., allegedly discloses that “[a] back cover assembly is provided for use in a device including a housing having a plurality of walls forming an enclosure. A blower mechanism is adapted to cause exhaust air to flow from an interior of the housing to an exterior of the housing. The back cover assembly is located in proximity with the blower mechanism, and includes an acoustical chamber adapted to permit exhaust air from the interior of the housing to pass therethrough. The acoustical chamber is adapted and constructed to reflect acoustical energy back into the blower mechanism. In an embodiment, at least one interior surface of the acoustical chamber is lined with a sound absorbing material such as polyurethane polyester foam. The acoustical chamber can include a front wall with at least one inlet open to blower mechanism, and a rear wall with at least one outlet. The outlet is in fluid communication with the at least one inlet on the front wall, and is open to the exterior of the housing. In order to provide the necessary acoustical reflectivity, the at least one inlet and the at least one outlet can be placed out of axial alignment with one another. For instance, where the at least one inlet is located at a top portion of the front wall, the at least one outlet may be located at a bottom portion of the rear wall. The at least one inlet and outlet can also be located at opposite sides of the chamber. Where there are a plurality of inlets and outlets, the plurality of inlets and outlets may be arranged to form respective inlet/outlet pairs. The acoustical chamber can be provided with at least one divider substantially spanning the space between the front and rear walls. The at least one dividers defines subchambers within the acoustical chamber, with each subchamber enclosing at least one inlet/outlet pair. The device with which the back cover assembly is associated may be provided as a disk array, such as a RAID system. Also disclosed is a method for reducing the amount of noise emitted by a device.” See Abstract.
U.S. Pat. No. 6,301,108, issued to Stockbridge, allegedly discloses “[a] fire containment and air flow control mechanism for a device or chassis housing electronic components. The electronic components generate heat during operation of the device. An aperture in the housing permits warm air generated within the chassis to escape into the environment to cool the circuit board or card. A trap door is provided for the aperture for purposes of fire containment. Normally, the trap door is open, allowing the warm air to escape through the aperture. The trap door is moveable relative to the housing between a first position, in which the trap door does not cover the aperture, and a second position, in which the trap door substantially obstructs the aperture. A temperature sensitive material, such as a nylon or other polymeric filament that melts when subject to sufficient heat or flame, is operatively connected to the trap door. The temperature sensitive material is transformed, e.g., by melting, upon exposure to sufficient heat or flame within the device so as to cause the trap door to move to the second position relative to the aperture. In this position, the trap door substantially prevents migration of any flame present within the device through the aperture. For example, the trap door may be held away from the aperture by the filament, and when the filament melts the door swings by gravity or drops into a closed condition relative to the aperture.” See Abstract.